Controlled width pulse generator



M. H. EANNE CONTROLLED WIDTH PULSE GENERATOR Filed June 2"?,

steep sides.

Patented Peb. 7, i956 2,496,543 .CONTROLLED WIDTH PULSE vGfENERATO',

"-Mortn l'Kanner', "deceased, l'lateof New` York;

'N.`Y.,f`1by^ Samuel iKanner, administrator, New

fierk, N. ry., rassignor, by t-.rnesne vassignments,

.'tozthe United'statesof Americafas represented 'by theSecretaryA of War Applicatonl une 27, 1944, lSerial yNo:"542,343

23': Claims. i1

Ihis invention relates to 'a *communication ing voltage i pulses having a duration 1 under accurate control r with the pulses themselves? having In' theoperation of manyfcommu- `nication systems,rectangular vltage'fpulsesl hav- 4ing steep *leading and trailing 4sides-fare fneces sary and in such instances thedurationotfthe fpulse `mayalso ll'la'veto be necessarily accurate.

"Thus, in-many-sySterns,pulsesA havingaY duration of the 'order ofv'one microsecond-or'vlessare required' -to Ypermit 'large peak i power without ex- Yceeding the Aaverage f power requirements Y of the system. VInpulsesl having such short EtimeA duravtion,tlfie'slope ofthe two sides of thepulSe must 4beisteepin order that'the ypulse as a Wholemay 'be considered -as 'generally 'rectangular'.

"Referring to the drawing, f' Fig. il .illustr ates an 'f embodiment of the inventionf-while-Fig. l2 shows some voltage curves 'illustrating 1 the operation thereof.

The invention `in vgeneral* provides i for the application of two#timedisplacedlpulses-'toithe*con- -trol and anode electrodes r`of an yelectron `v'dis- Charge 'device whereby ythe -conducting period-'of series v'combination of inductanee 12'ia'nd-y resistance l3 'to a lpulse-forming network'll. l"Pulseforming network-4,as shown, is aftypefhaving .condensers 6 and 8 on opposite -sides ofin'ductan'ce l, the condensers having` one common terminal grounded as shown. 'Such'pulse-forming 'networks vare well known and one type is illustrate'dfand'described n the application of J. C. Street, Serial No. 479,660 led"March1`8,'1`943. Other types .of pulse-forming networks may be '.used. The output of network 4 is applied'to anode'fl ofan electron dischargedevice H. .Electron discharge device Il has a control grid l2 which may be biased .through a resistance `il?, and battery vHl rconneetedlbetween nthe rgridrahd :,ground. Cathode l5 of tube limaybeconnected to ground through a suitable load resistor 16. As shown here,`tube Il is of theligasllled type-such as the Iso-'calledy thyratron.

is I adapted to i generate @Waveshaving i'the'general shape fsho-wn 1in A, lthe 'ltiine duration ofi-these Ywavesbeingfcontrolled by the` time constantsrof thex grid circuits;A alias` we'll'lknown.

.Electrondischargefdevice fv Il I Histconne'cted'asia resistor, .Erom' the high terminal L'f lfthis 'lload l'resistor 'a 'line igoes to an f output `'terminal 331,

33 being the other grounded Iioutpu-i. terminal.

denser 40 to a delay .'cir'cuit fdly-which'rmaybe 'of Iamr suitable type. 'As shown, "this iis l'anlarti- .ficial transmission lihe- 'consisting .of iiiductances 424-2 .and 43 connected in 'series with ygrounded Tcondensers L44 and V45 L'bein'g :connected Ion fo'prposite sides of `irrductance 43. i Such varticial `llines. :arel `well lknown` inthe f arteiand may hercon- 255' Ypulses. Such v-delays "maybe 'of'rthe order forca fraction 1of .'a f'microsecond Y up :to several 1 microeseconds 'and even longer, the rdelaybeing I'dcterstructedlto provid-e accurate delays 'lier/:voltage mined by the constants of the line "fas-well -as "the number of sections.

Line `T36 'is connected fdirectly 'Sto The multivibratorfisfadaptedto-1gener`ate 2genand A'applied through `2 blocking c'ondenser `212111430 3The=-repetition rate l-of the multivibrator vvill'd-etermine the repetition rate-'fft'helnalipuise outrput and may be varied withinfwide llimits inf-a mannerfwell known -to r'the art.

` The positive pulse of'fthe A' multivibrator output when' appliedto grid |12 causesfelec'tronv` discharge device Il to breakdown, assumingi'thatfthereis a potential impressed racross "from vith'e Aanode'ito the cathode. lBy having fthe `vlanode ptertial in the form of pulses generated by pulse-forming network 4, a more accurate control over the action of the system is obtained. Preferably re.

sistance I6 in the cathode circuit of electron discharge device II is of such a value as to constitute a characteristic impedance for pulse network 4. When such a relationship is established, maximum efoiency results. It is assumed that the value of the various resistances between B-I- and anode I is such that gas tube II will be extinguished upon the expiration of the pulse from network 4. This will be caused by the drop through the resistances and inductances being suiiiciently great so that the potential across tube II will be insufcient to support ionization.

The pulse output applied to anode I0 may thus assume the shape shown in curve B. During the coincidence of the pulse voltage applied to anode I0 and the positive pulse applied to control grid I2, there will be a pulse passing through load reisstor I6. Curve C shows the voltage pulse which would appear across resistance I6 in the absence of any additional connections to this load resistance. It is understood that curves B and C are not necessarily drawn to scale and the shape of the voltage curves depends in some measure upon whether tube II saturates or not. Under some conditions the voltage curve across load resistor I6 and in the absence of the rest of the connections thereto might be approximated by a curve similar to B. In any event, a pulse does appear across load resistor I6. Assuming that the pulse is positive as shown in curve C, then the pulse is immediately applied across electron discharge tube 41. On the other hand, grid 46 of this tube is biased so that tube 41 will not conduct until the delayed pulse appears on the grid thereof. When this occurs, tube 41 will conduct and form a substantially short circuit across resistance I6 for a predetermined time interval.

The time duration of the pulse at output terminals 31 and 38 will naturally be determined by the amount of delay in delay line 4I, assuming that this delay is less than the duration of the pulse across resistor I6. Since the delay due to network 4I may be accurately controlled, it is evident that the duration of the output pulse shown in D is subject to careful control. The steep sides of the pulse generated by the sudden breakdown of tubes I I and 41 will make for steep pulse sides.

It is clear that pulse-forming network 4 may be omitted if desired. In that case, if tube I I is a gas discharge device, then the drop through suitable resistors will be relied upon to extinguish the tube so that grid I2 may re-establish its control. Tube I I need not necessarily be a gas discharge device but may instead be a vacuum tube. If tube I I isavacuum tube, it may be used either with or without pulse-forming network 4.

Control grid I 2 of tube I I may be pulsed either by the multivibrator shown or by any other suitable source. In the event that tube II is a gas discharge device, the steepness of the pulse applied to control grid I2 is not important, providing that it is steep enough to cause a sharp trigger action. However, in the event that tube II is a vacuum tube, then the pulse shape impressed upon control grid I 2 does become important since this will determine the shape of the output pulse across load resistor I6. By having the combination of pulse forming network 4 and a multivibrator operate upon a grid control gas tube, exceedingly sharp output pulses may be obtained.

Similarly, tube 41 may be a vacuum tube if desired. However, as with tube I I, a gas tube, when broken down, provides a low resistance path and this is an advantage. It is also possible to reverse the grid and plate connections of tube 41 so that the delayed pulse is applied to the plate while the undelayed pulse is applied to the control grid. However, the arrangement shown is preferred since delay line 4I attenuates the pulse.

What is claimed is:

1. A pulse-forming system comprising an electron discharge device having a cathode, control grid and anode, an anode circuit including a delay line, means for applying control pulses to said control grid at predetermined intervals, causing conduction through said tube at predetermined intervals to generate output pulses, a resistance through which the current of said tube passes and across which said output pulses appear, a second electron discharge device having an anode control grid and cathode connected across said resistance in a direction to tend to cause current ilow through said second device upon existence of an output pulse, connections including a delay line between said resistance and said second device control grid to apply said delayed output pulses thereto, and an output circuit between the anode and cathode of said second device.

2. A pulse generating system comprising a grid control gas tube, said gas tube having a cathode, control grid and anode, a load resistor in the cathode circuit of said gas tube, a delay line connected in the anode circuit of said gas tube, means for applying grid potentials at periodic intervals, said potentials being sufficient to cause tube breakdown, said load resistor having pulses formed therein, a second gas tube having a cathode, control grid and anode, means for connecting said anode and cathode of said second tube across said load resistor so that said pulses tend to cause space current through said second tube, a delay line connection between the control grid of said second tube when its grid is driven positive and one terminal of said load resistor so that said pulses tend to drive said second grid positive after an interval established by said delay line, and an output circuit between the anode and cathode of said second device.

3. The system of claim 2 wherein the voltage supply source of the control grid of said iirst tube is a irst pulse generator and wherein the plate voltage supply for said rst tube is a second pulse generator that cooperates with said rst pulse generator, said two pulses having durations longer than that of the desired output pulse.

SAMUEL KANNER, Administrator of Estate of Morton H. Kanner,

Deceased.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 2,266,154 Blumlein Dec. 16, 1941 FOREIGN PATENTS Number Country Date 487,982 Great Britain June 29, 1938 491,741 Great Britain Sept. 8, 1938 

